Mayweather's pay, based on his cut of advance pay-per-view sales, will go higher when total pay-per-view buys are tallied. HBO is charging $69.95 for the bout, a World Boxing Assn. super-welterweight title defense for Cotto (37-2, 30 KOs).

Fight promoter Richard Schaefer said this week that the bout could generate more than 1.5 million buys.

The prior Nevada record for a fighter's guaranteed purse was $30 million, accomplished three times by Mike Tyson in both of his fights against Evander Holyfield and another against Frank Bruno.

The combined guaranteed purses of Mayweather and Cotto, who'll get $8 million, fell $1 million short of Nevada's total purse record, still held by Tyson and Holyfield in their June 1997 rematch at the MGM Grand, when Holyfield earned $11 million.

Mayweather (42-0, 26 KOs) is a near 8-to-1 favorite (-750) to defeat Cotto.

Nevada officials announced earlier this week that the fight's referee will be Tony Weeks, with Patricia Morse-Jarman, Robert Hoyle and Dave Moretti serving as judges.

The boxers are scheduled to weigh in Friday afternoon for the 154-pound fight.